Loading a 9x12 Voigtländer Avus

I recently bought a Voigtländer Avus 9x12 cm camera, and I plan to use it primarily with paper negative work; it came with a few plate holders (with the septums/sheaths/film inserts or whatever they are called). I am finding it a real challenge get the septums (once loaded with the paper negative) to snap into place in the plate holder without having to press down on the paper negative, risking damage, etc.

Does anyone have any recommendations of film loading technique for this camera? Would it be better in the long run to try to put some kind of shim in the plate holder, in place of the septum?

Reverse the sheath, so that you push the folded-over edge with your finger. It should only take a gentle push against the spring in the bottom of the holder - unless you have the top-spring type of holder, in which case you pull the spring out with one fingernail while using the other hand to push gently on the edges.